The spinal column is a structure principally composed of vertebrae and intervertebral disks, along with ligaments and muscles, with primary functions of supporting the body and protecting the spinal cord and associated nerve roots. The spinal column's body support functionality involves distribution of weight from the various extremities and the torso to the pelvis and legs. As individuals age, various adverse spinal column conditions may develop that often result in back pain. Examples of such conditions include spinal stenosis, thickening of spinal column constituent bones, facet antropathy, facet joint arthritis, facet synovial cyst, annular tear, painful disc disruption, and segmental instability. A number of these (and other) spinal conditions involve compression of the spinal cord or one or more nerve roots emanating from the spinal cord.
A number of efforts to address such spinal column conditions have attempted to address nerve compression issues by spreading adjacent vertebrae farther apart or at least maintaining a space between them during movement (i.e., stabilization), in order to “decompress” the impinged nervous tissue. One general type of device developed for this purpose has been interspinous implants for implantation between adjacent spinous processes. Examples of such devises are described in U.S. Pat. No. 6,695,842, U.S. Patent Application Pub. No. 2004/0181282, and others.
Although advances have been made in the treatment of spinal conditions and in interspinous implants more specifically, improvements would still be desirable. For example, several challenges with interspinous implants thus far have been that they can be difficult to implant, they can become dislodged over time due to patient movement, they can be difficult to remove if necessary, and they can damage the spinous processes adjacent to where they are implanted. The embodiments described in this application seek to address at least some of these shortcomings.